1. Field of the Invention
The invention relates to a sprocket wheel and chain for imparting rotary motion to the sprocket and to a construction of sprocket wheel prevents disengagement of the chain. More particularly, the invention relates to a motorcycle sprocket and chain for use during conditions of severe stress, such as during motorcycle racing.
2. Description of the Prior Art
U.S. Pat. No. 1,181,175, issued May 2, 1916, to Shapiro, shows a sprocket wheel flange extending a short distance above the radial extent of a chain associated with the sprocket. Little guiding action can be expected from the flanges of Shapiro in view of the wide separation shown between the flanges and the chain itself, and impact on the flange could reasonably be expected to cause the flange to deform and interfere with normal movement of the chain. U.S. Pat. No. 4,044,621, issued Aug. 30, 1977, to McGregor, Sr., et al, shows a sprocket structure and chain guard having a single plate lining only one edge of one of a plurality of driving sprockets. No application is disclosed for a driven sprocket, nor do McGregor, Sr., et al, suggest a structure constructed to prevent throwing of the chain from a driven sprocket. Other patents relating generally to sprocket and chain assemblies include the following:
U.S. Pat. Nos: 579,742 - Mar. 10, 1897 - Cottie, et al. 3,477,303 - Nov. 11, 1969 - Brilando.
A disadvantage of existing racing motorcycle sprocket and chain assemblies is the frequent occurrence of throwing of chains or crawling of chains off the rear motorcycle sprocket during conditions of motorcycle racing over rough terrain at maximum speeds. Moreover, lateral motion of the driving chain has been known to interfere with other motorcycle components located in proximity thereto, such as the piston portions of shock absorbers along the upper chassis, particularly during deceleration of the motorcycle, in which phase of operation the upper portion of the chain undergoes slackening.